1. Field of the Invention
This invention relates to a method of manufacturing a nozzle plate for an ink jet recording head. It also relates to an ink jet recording head comprising such a nozzle plate and an ink jet recording apparatus comprising such an ink jet recording head.
2. Related Background Art
An ink jet recording head used for an ink jet printing system (liquid jet recording system) generally comprises fine discharging orifices, ink flow paths communicating with the respective discharging orifices and liquid discharging energy generating sections disposed at a part of the ink flow paths so that, in each of the ink flow paths, the energy generated by the liquid discharging energy generating section is applied to the liquid (ink) in the ink flow path to cause it to discharge from the orifice. The discharging orifices are integrally provided in a discharging orifice plate which is a member for forming the discharging orifices (hereinafter referred to as xe2x80x9cnozzle platexe2x80x9d).
A number of methods have been proposed for manufacturing a nozzle plate for an ink jet recording apparatus.
For example, xe2x80x9cHewlett Packard Journal 36, 5 (1985)xe2x80x9d discloses a method of manufacturing a nozzle plate for an ink jet recording apparatus provided with discharging orifices, each of which is fine and tapered along the discharging direction. As shown in FIGS. 7A and 7B, the proposed method comprises the steps of providing a resist 52 on a metal substrate 51 and arranging a mask 53 on the resist 52 (see FIG. 7A), electroforming nickel to cover the resist (see FIG. 7B) and peeling off a nickel plate 54 from the metal substrate. However, since the plate produced by electroforming evenly grows from the corners 55 of the resist both in the vertical direction and in the horizontal direction as shown in FIG. 7B, the distance (or density) of arranging discharging orifices and the thickness of the nozzle plate provide a trade-off. Thus, any attempt for producing discharging orifices arranged at a short distance d in order to realize high definition recording can result in a reduction of a nozzle plate thickness t, to thereby give rise to handling problems when bonding the nozzle plate to a member for forming ink flow paths.
Methods proposed to bypass the above problem are disclosed in Japanese Patent Application Laid-Open Nos. 62-234941 and 63-502015.
The method proposed in Japanese Patent Application Laid-Open No. 62-234941 relates to the two-layered structure of a resist which operates as a mask on a metal substrate, whereas Japanese Patent Application Laid-Open No. 63-502015 discloses a method of manufacturing a nozzle plate comprising a step of forming a first resist layer, an electroforming step, a step of forming a second resist-layer and an electroforming step, wherein the ink discharging orifices and the ink flow paths are formed simultaneously.
However, any of the above described methods cannot provide a resist layer having thick areas that are etched to show a desired profile and involves a complex manufacturing process to raise the overall manufacturing cost. Additionally, in these method, a water repellency treatment is carried out on the face of the discharging portion of an ink jet recording head in order to improve the discharging performance of the head (accuracy of landing ink droplets on a recording member), the water repellency treatment cannot be conducted after the electroforming because the face of the discharging portion is formed at the surface side of the metal substrate.
In view of the above problems of the prior art, it is therefore an object of the present invention to provide a method of manufacturing a nozzle plate having a desired thickness for an ink jet recording head at a low cost regardless of the density of discharging orifices, with which a water repellency treatment can be carried out without difficulty. Another object of the present invention is to provide an ink jet recording head having a nozzle plate manufactured by such a method and an ink jet recording apparatus comprising such an ink jet recording head.
As a result of intensive research efforts, the inventors of the present invention have succeeded in achieving the above-objects. The first aspect of the present invention is to provide a method of manufacturing a nozzle plate for an ink jet recording head, which comprising:
(a) a first step of forming a layer of a resin comprising a benzene ring on a metal substrate;
(b) a second step of patterning the layer of the resin by means of an excimer laser and partially exposing the metal substrate;
(c) a third step of forming a metal layer having a thickness smaller than that of the resin layer on the exposed surface of the metal substrate by electroforming; and
(d) a fourth step of separating the metal layer from the metal substrate and the resin layer.
The second aspect of the present invention is to provide a method of manufacturing a nozzle plate for an ink jet recording head according to the first aspect which further comprise a step of conducting a water repellency treatment on the surface of the metal layer.
The third aspect of the present invention is to provide a method of manufacturing a nozzle plate for an ink jet recording head according to the first aspect, wherein in the third step of forming a metal layer, a plurality of metal layers is superposed and the last metal layer superposed as the surface layer comprises nickel as a main component and TEFLON non-stick coating particles.
The fourth aspect of the present invention is to provide a method of manufacturing a nozzle plate for an ink jet recording head according to the first, the second or the third aspect, wherein the metal layer is made of nickel.
The fifth aspect of the present invention is to provide a method of manufacturing a nozzle plate for an ink jet recording head according to any one of the first to the fourth aspects, wherein the second step of patterning the layer of a resin is conducted in two stages of using two different masks to integrally form ink discharging orifices and ink flow paths.
The sixth aspect of the invention is to provide an ink jet recording head comprising a nozzle plate manufactured by a method according to any one of the first to the fifth aspects.
The seventh aspect of the invention is to provide an ink jet recording apparatus comprising an ink jet recording head according to the sixth aspect.
It may be clear from the above that, with a method of manufacturing a nozzle plate according to the invention,
(i) the density of discharging orifices and the thickness of the nozzle plate can be independently controlled to provide a greater extent of designability;
(ii) the overall manufacturing process can be controlled with easy because of a reduced number of manufacturing steps to allow a reduced manufacturing cost;
(iii) the face of the discharging portion can easily be treated for water repellency; and
(iv) the nozzle plate can be made to show a desired thickness and a high definition nozzle pattern.
An ink jet recording head prepared by using a nozzle plate according to the present invention and an ink jet recording apparatus comprising such an ink jet recording head operate excellently with an enhanced accuracy of hitting the targets with ink drops because each of the discharging orifices has a smoothly and evenly tapered profile.